﻿<p>This entity describes edge members with varying profile properties.  Each instance of <em>IfcStructuralCurveMemberVarying</em> is composed of two or more instances of <em>IfcStructuralCurveMember</em> with differing profile properties.  These subordinate members relate to the instance of <em>IfcStructuralCurveMemberVarying</em> by <em>IfcRelAggregates</em>.</p>

<blockquote class="note">
NOTE&nbsp; A curve member whose variation of profile properties can be sufficiently described by a start profile and an end profile (e.g. tapers) shall be modeled as a single direct instance of the supertype <em>IfcStructuralCurveMember</em>.
</blockquote>

<blockquote class="note">
NOTE&nbsp; It is recommended that structural activities (actions or reactions) are not connected with aggregated <em>IfcStructuralCurveMemberVarying</em> but only with the <em>IfcStructuralCurveMember</em>s in the aggregation.  That way, difficulties in interpretation of local coordinates are avoided.
</blockquote>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x2.
</blockquote>

<blockquote class="change-ifc2x4">
IFC4 CHANGE&nbsp; Use definition changed.
</blockquote>

<p><b><u>Coordinate Systems</u></b>:</p>

<p>See definitions at <em>IfcStructuralItem</em> and <em>IfcStructuralCurveMember</em>.  The local coordinates of the aggregate are derived from those of its parts.  Length measures in local x direction of the aggregate depend on continuity and lengths of the parts.  The <em>Axis</em> of the aggregate shal be the same as the <em>Axis</em> of the part at the start of the aggregate.</p>

<p><b><u>Material Use Definition</u></b></p>

<p>Only the individual parts (direct instances of <em>IfcStructuralCurveMember</em>) carry material and profile information.</p>